This paper presents a comparison between the maximum von Mises stress values an maximum displacements appeared under occlusal loading in different areas of a mandibular class I Kennedy removable partial dentures (RPD) with ball attachments, in two situations: teeth supported only, and implant and teeth supported. The first 3D model was created for class I Kennedy RPDs with only six anterior teeth as abutments. The second 3D model was created for the same situation, adding two implants, placed bilaterally, each in the second molar area. On the implants were also positioned ball attachments, providing support and retention for the denture. All materials were considered homogeneous, isotropic and having linear elasticity. Our results demonstrate important differences between the two possible prosthetic treatment solutions for the same class I Kennedy situation, showing that associating an implant for each free-end saddle reduces the maximum von Mises stress and the maximum displacement's values in the RPD. Keywords-RPD, ball attachments, implants, FEAI.